1. Field of the Invention
The invention relates to a control of a vehicle equipped with an electrically heated catalyst.
2. Description of the Related Art
A vehicle equipped with an internal combustion engine is generally equipped with a catalyst that purifies exhaust gas from the internal combustion engine, that is, removes undesired substances from exhaust gas. If this catalyst has not attained its activation temperature, the catalyst cannot sufficiently purify exhaust gas. Therefore, an electrically heated catalyst (hereinafter, referred to as “EHC”) constructed so that the catalyst can be heated by an electric heater or the like has been proposed.
For example, Japanese Patent Application Publication No. 2009-167875 (JP-A-2009-167875) discloses a technology of avoiding deterioration of emissions of a vehicle equipped with an internal combustion engine whose exhaust gas is purified by an EHC, and an electric motor that is driven by electric power supplied from a battery that is rechargeable by an external electric power supply, that is, a so-called plug-in hybrid vehicle. Specifically, if the amount of stored electricity (or state of charge) of the battery is less than a predetermined value and the vehicle is disconnected from the external electric power supply, the technology determines that the engine is likely to be started, and then electrically heats the EHC so as to avoid deterioration of emissions.
However, despite the heating of the EHC prior to the starting of the engine as described in Japanese Patent Application Publication No. 2009-167875 (JP-A-2009-167875), there is still a risk of the EHC failing to sufficiently purify exhaust gas and therefore allowing deterioration of emissions if the engine is started with high load so that a large amount of exhaust gas passes through the EHC.